The prior art is replete with different complementary metal-oxide-semiconductor field effect transistor (MOSFET) technologies. For example, enhancement mode metal-oxide-semiconductor field effect transistors (EMOSFETs) on compound semiconductors can employ standard-refractory metal gates with a metal work function of about 4.6 eV, an undoped channel to provide enhancement mode operation (positive and negative threshold voltage for n-channel and p-channel devices, respectively), and self-aligned ion implants to form low resistivity source and drain extensions and Ohmic contact regions. However, only p-channel EMOSFETs have been successfully fabricated on the compound semiconductor GaAs in the past. For n-channel EMOSFETs on GaAs, the implant activation temperature for donors of >700° C. is incompatible with Ga2O3—GaAs interface stability. The Ga2O3—GaAs interface can only be preserved for temperatures ≦700° C. and this interface is completely destroyed for temperatures above 700° C. during activation anneal of donor implants.
The prior art also includes compound EMOSFET technology using standard metal gates with a metal work function of about 4.3 to 4.6 eV, a channel doped to opposite conductivity type by ion implantation to provide enhancement mode operation (e.g., positive threshold voltage for n-channel devices) and ion implants to form low resistivity source and drain extensions and Ohmic contact regions. Since the n-type implants are annealed prior to gate oxide deposition, the oxide-GaAs interface is not affected by high temperature during implant activation. However, the subsequent gate oxide deposition is inevitably conducted on an exposed semiconductor surface, which leads to a high defect density at the oxide-semiconductor interface. The high defect density only allows the fabrication of devices with about 1% of anticipated performance, rendering the devices essentially useless.
Accordingly, it would be desirable to have a high performance complementary semiconductor FET technology that is compatible with gate oxide technology. Furthermore, other desirable features and characteristics of the invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.